The present invention relates to a nonvolatile semiconductor memory device and its operation program, and relates to, for example, a nonvolatile semiconductor memory device and its operation program that use a variable resistance element.
A memory that holds the contents stored therein even after a power supply is turned off is called a nonvolatile memory (or a nonvolatile semiconductor memory device), and is used for various types of electronic devices in which integration has been enhanced. The nonvolatile memory includes, for example, a flash memory in which data is recorded using a floating gate and data is written by units of blocks and a resistance change type memory (Resistance Random Access Memory, hereinafter it will be referred to as an “ReRAM”) which records data using changes in a resistance and can be randomly accessed.
Since the amount of the current necessary to write data into the ReRAM is smaller than that in the flash memory and the writing speed in the ReRAM is higher than that in the flash memory, power consumption can be reduced in the ReRAM. The ReRAM is therefore regarded to be promising as a memory to be mounted on a battery driven portable electronic device or the like.